What's the average cost to build a tunnel?

If I were to build a tunnel made primarily out of wood that is about 7 feet tall and 8 feet long and 4-5 feet wide, how much would it cost?

-Zoe

Zoe, I'm afraid there is no average cost for building a tunnel and if anyone should tell you there is, be very suspicious. There are two issues that may greatly affect the cost of your tunnel: whether the location allows digging equipment to be brought in and used and what the contractor might run into once they start digging.

As you can imagine, trying to dig something like this by hand would require a lot of labor and could take quite some time. All of that adds up to mean that a contractor might be charging a lot for the project. And then there is the question of the dirt that's being removed as it has to go somewhere. It may have to be wheeled to where it can be loaded into a truck and hauled away or to somewhere in your yard where it can be spread. Again, a lot of labor would be involved either way.

If where the tunnel is to be located permits access by machinery and trucks, the job should be much easier and faster to complete. There could still be some hand labor involved, but much of the work should be able to done by digging machinery. And the dirt could be loaded into a truck as they were digging which should also make the project go a little more quickly. Another concern that can have an impact on the project cost is whether any trees and shrubs may need to be moved before digging can commence. Larger trees may not be able to be moved and could have to be cut down.

However, very few excavating contractors give a price for a project without including a "rock clause." That clause normally states that any labor and machine time required to remove large rocks is extra or not a part of the contract price. Some rocks can be broken up and removed with a jackhammer type piece of equipment that is attached to a backhoe, but extremely large rocks must be cracked with explosives before they can be removed. That's something to keep in mind if you plan on having the tunnel fairly close to your home.

The best advice I can give you is to have an excavation contractor visit your home to get an idea of what your project might entail. They should be able to give you an approximate cost for the job providing nothing unusual is discovered beneath the surface.